Tire parameter sensing systems for vehicles typically include a plurality of tire-based units and a single vehicle-based unit. Each tire-based unit has an associated tire of the vehicle and is operable to sense at least one parameter of the tire. The sensed parameter(s) may include temperature, pressure, etc. Each tire-based unit is also operable to transmit a parameter signal indicative of the sensed parameter(s) to the vehicle-based unit. The vehicle-based unit is connected to a display. In response to receiving a parameter signal from a tire-based unit, the vehicle-based unit outputs a signal to the display. The display is responsive to the signal for displaying the sensed tire parameter(s).
It is common for a tire-based unit of a tire parameter sensing system to be fixed for rotation with its associated tire. Typically, the tire-based unit is fixed to a rim upon which the tire is mounted. The rim and mounted tire collectively form a wheel assembly of the vehicle. The wheel assembly rotates relative to a body of the vehicle during movement of the vehicle. During the rotation of the wheel assembly, the tire-based unit moves relative to the vehicle-based unit. During a portion of each rotation of the wheel assembly, the rim of the wheel assembly becomes interposed between the tire-based unit and the vehicle-based unit. When the rim is located between the tire-based unit and the vehicle-based unit, the rim may block the parameter signals that are transmitted from the tire-based unit to the vehicle-based unit. Additionally, when the tire-based unit is located at certain rotational positions relative to the vehicle, attenuation of the parameter signals may occur as the parameter signals pass through the structure of the tire. As a result, a signal to noise ratio of a parameter signal that is received by the vehicle-based unit may be too low for enabling the vehicle-based unit to accurately extract the sensed parameter(s).
A communication zone is associated with each tire-based unit of the tire parameter sensing system. Parameter signals transmitted from a tire-based unit located within the communication zone are generally received at the vehicle-based unit with a signal to noise ratio sufficient for the vehicle-based unit to accurately extract the sensed parameter(s). Typically, the communication zone is located between the rim of an associated wheel assembly and the vehicle-based unit. The tire-based unit passes into and out of the communication zone during rotation of the wheel assembly. When the tire-based unit is located outside of the communication zone, parameter signals transmitted from the tire-based unit are less likely to be received at the vehicle-based unit and, when received, are likely to have low signal to noise ratios. A tire parameter sensing system for transmitting parameter signals while the tire-based unit is in the communication zone is desired.